Project Summary/Abstract: Ambulatory children with cerebral palsy (CP) walk predominately in low intensity stride rates with little variability, thus limiting their walking activity and ability to participate in daily life. In contrast, typically developing (TD) children engage in short bursts of intense walking activity interspersed with varying intervals of low intensity walking within daily life. In order to optimize motor learning, active participation, task-specific training and multiple repetitions or massed practice is required to learn new motor skills. Short bursts of vigorous intensity locomotor treadmill training (SBLTT) alternating with low/moderate intensity was specifically designed to mimic activity patterns of TD children in a massed practice format. Pilot data suggests that SBLTT is feasible and enhances walking capacity and performance in daily life for children with CP. The objective of this application is to examine the effect of SBLTT versus an equivalent dosage of traditional locomotor treadmill training (TLTT) on the primary outcomes of walking capacity and performance in children with CP. This protocol will also examine whether the effects of SBLTT on walking capacity and performance are mediated by improvements in in muscle power generation. The scientific premise is that SBLTT, that approximates the walking intensity patterns of typically developing (TD) children through a clinically feasible massed practice protocol, will be more effective than TLTT in improving walking capacity and performance. We hypothesize that SBLTT strategies for children with CP modeled on activity patterns in TD children, will be positively mediated by muscle power generation and subsequently improve walking capacity and community walking performance and mobility. We will test the following specific aims. Aim #1. Determine the immediate and retention effects of short-burst interval LTT (SBLTT) on walking capacity in ambulatory children with CP. Walking capacity will be measured by self-selected gait speed and the one minute walk test. Aim #2. Examine the effects of treatment on community-based walking activity performance and mobility. Walking activity performance will be captured by accelerometry. Community walking mobility individualized by home versus community locations will be measured with a novel combination of global position system and accelerometry. Aim #3. Explore whether the effects of SBLTT on walking capacity and performance are mediated by muscle power generation. This project is innovative because it focuses novel task-specific approach for addressing walking limitations in children with CP and implements an individualized community locations outcome. The proposed research is significant because it will be the first step in a continuum of research that is expected to direct locomotor training protocols and rehab strategies across pediatric disabilities and positively effecting the community walking performance and mobility for children with CP. Increased understanding of the muscular mechanisms by which children with CP respond to SBLTT are expected. Such knowledge has relevance to the health and functional benefits of enhanced mobility and physical activity across the life span.